Spiders Common At the Cottage

This document to be used as reference only.

All spider bites should be considered dangerous.

If you get bitten by a spider, see your doctor immediately.

     Spiders are a common and familiar group of arthropods. They are similar to insects in that they both have exoskeletons (their skeletons are on the outside of their bodies) and jointed legs. However, spiders differ from insects in several ways. See Table A

Any arthropods that share the same characteristics as spiders are known as arachnids. Other arachnids, or spider relatives, include ticks, daddy-longlegs, scorpions, and mites.

Another difference between spiders and insects is that all spiders can produce silk throughout their lifetime. However, just a few insects can produce silk, and then at only certain times during their life. Spiders use silk to build webs and other types of snares, egg cases, draglines, and refuges. Silk is also produced by spiderlings (young spiders) during a process called ballooning in which the spiderlings shoot silk into the air and are carried away by the wind.

Spiders are predators, feeding mainly on insects. Spiders are considered beneficial because of the large number of insects they prey on, including a number of pest species. All spiders have venom and are therefore venomous. However, most spiders are harmless to people. They are very shy and usually remain hidden in undisturbed areas. Many are active only at night. They are not aggressive and they will try to escape when confronted. Few spiders bite, even when coaxed. Fortunately, the bites of most spiders are less painful than an average bee sting. However spider bits can be serious as bee stings if you have an allergic reaction or if you have come in contact with a poisonous spider.

COMMON SPIDERS IN AND AROUND THE COTTAGE AN D HOME

Spiders can be divided into one of two groups depending on how they capture their prey: hunting (sometimes known as wandering) spiders and web-building spiders. All spiders produce silk, but hunting spiders do not construct webs to capture food. Instead, they rely on their quickness and relatively good eyesight to capture prey. Web-building spiders construct webs in rather quiet, undisturbed places to capture their food. They live in or near their web and wait for food to come to them. They generally have poor eyesight and rely on sensing vibrations in their web to detect prey.

(NOTE: Sizes given under spider descriptions represent the length of the body not including the legs). 

HUNTING SPIDERS

Jumping spiders  are common spiders outdoors and indoors. They are active during the day and are often found around windows, ceilings, walls, and other areas exposed to sunlight. Jumping spiders are generally small to medium-sized (about 1/5 - 1/2 inch long) and compact-looking. They are usually dark-colored with white markings, although some can be brightly colored, including some with iridescent mouthparts. These spiders move quickly in a jerky, irregular gait. They get their name from their ability to leap on their prey, often jumping many times their own body length. Like most spiders, jumping spiders have eight eyes, of which the two middle eyes are particularly large. Jumping spiders have the best vision of spiders, seeing objects up to 8 inches away.

Wolf spiders  are common spiders outdoors and are occasionally seen indoors. They are moderate to large-sized spiders (1/4 - 3/4 inch long). Wolf spiders are found on the ground or under stones in a wide variety of habitats, such as forest floors, grassy meadows, swamps, docks and bogs. Some even like to live underground. They commonly hunt during the day or at night when it is warm. Wolf spiders are dark-colored, usually brownish or grayish, with white markings.

Fishing spiders, also known as dock spiders, are typically seen around ponds, swamps, slow-moving streams, and nearby vegetation. They may occasionally be found indoors. Fishing spiders are the largest spiders in the Upper Midwest (1 inch long). With legs spread out, some fishing spiders cover as much as 4 inches. They are generally dark-colored, usually brownish or grayish, with white markings. Fishing spiders can "skate" across water and can dive underneath to capture prey. In addition to insects, fishing spiders can also catch tadpoles, small fish, and other small vertebrate animals.

Sac spiders (also known as two-clawed hunting spiders ) are common spiders on foliage or on the ground, and can be commonly found indoors. They are small to medium-sized spiders (1/5 - 2/5 inch long) and are usually yellowish or light-colored. Although sac spiders do not construct webs, they do build retreats from silk. Outdoors, they usually roll up leaves into a tube, or may construct a retreat under stones. Inside buildings, sac spiders are found in retreats in a variety of places, including high up on walls near ceilings.

Crab spiders are common spiders outdoors, but are not usually seen indoors. They are small to medium-sized spiders (1/10 - 2/5 inch long) ranging in color from yellow or red to brown or gray. The first four legs of crab spiders are crab-like, being held out to the sides. They are also usually longer than the back four. Crab spiders can walk forwards, sideways, or backwards. While many hunting spiders actively pursue prey, crab spiders wait motionless and ambush insects that pass closely by. Outdoors, crab spiders are often found on flowers but are also seen on stems or leaves.

 Gnaphosid spiders are common spiders outdoors. A specific gnaphosid spider known as a parson spider  is occasionally seen inside. The parson spider is a medium-sized spider (1/2 inch long) with a brownish body and gray abdomen with a white band running down over half the length of its abdomen. Parson spiders hunt at night. During the day, they are usually found outdoors under stones or loose bark in silken retreats. Indoors, they hide under objects or in cracks or crevices.

WEB-BUILDING SPIDERS

Comb-footed spiders  also known as cobweb spiders, are very common spiders outdoors and indoors. They are small to medium-sized spiders (about 1/8 - 3/8 inch long). Comb-footed spiders are usually brownish or grayish. They build irregular webs in many places, including wood and stone piles and in quiet areas of buildings, such as basements. A common type of comb-footed spider found indoors is the house spider (figure 7). It is grayish to brownish with chevron-like markings on its abdomen and a body length of over 1/4 inch.

Orb spiders  are common spiders outdoors near buildings, but are usually not found indoors. They range in size from small to large (1/8 - 1 inch long) and are found in a variety of colors, with some being brightly colored. Orb spiders have large, swollen-looking abdomens, including some that are oddly shaped. They make the classic round, flat, wheel-like web familiar to most people. 

The black and yellow argiope (are-JI-o-pee) spider , also known as the garden spider, is familiar to many. It is large (up to 1 inch long) and brightly colored black and yellow. Another common orb spider is the barn spider. It is large (4/5 inch long) and brownish in color. 

Grass spiders, a type of funnel weaver, are common outdoors and are occasionally found indoors. They are generally brownish or grayish with light and dark stripes near the head. They have long spinnerets and are moderate-sized (3/4 inch long). Grass spiders construct a large sheet web with a funnel they use as a retreat. These webs are commonly built on the ground, around steps, window wells, foundations, and low shrubs. 

CONTROL OF SPIDERS IN AND AROUND THE COTTAGE AND HOME

Spiders are common in homes during warm weather, although they can be found indoors any time during the year. Their numbers usually peak during late summer and fall, when they are sometimes found indoors searching for winter hibernation sites.

Spider control is usually challenging. It is difficult to eradicate all spiders from a home. It is also unnecessary. Properties located in areas favorable to spiders, such as by rivers, lakes, or fields, are more likely to have large numbers of spiders.

Tolerate spiders whenever possible. Because of their beneficial nature, they are very important to the environment. When tolerance is not possible, use an integrated approach using nonchemical methods supplemented with chemical means to reduce spider numbers.

OUTDOOR CONTROL

If it is necessary to reduce the number of spiders in and around your home, start with nonchemical methods including sanitation to prevent spiders from entering from the outside.

If it is necessary, supplement these methods with an insecticide application around the outside of your home. Spray under siding, in cracks and crevices, and other places where spiders may hide. General treatments on the siding or other surfaces are not as effective.

When treating the outside of a building, use ONE of the following insecticides:

INDOOR CONTROL

Regular housecleaning is very important in the control of spiders indoors. Large, persistent spider populations indoors indicate the presence of a significant insect population that serves as their food.

You can supplement your sanitation efforts with an insecticide treatment. Treat especially behind base-boards, in cracks and crevices, and other places where spiders may hide. General treatments on surfaces and fogs are not effective. Most insecticides labeled for ants and cockroaches are also labeled for spiders. These products are commonly found in aerosol ready-to-use cans.

CAUTION: Read all label directions carefully before buying insecticides and again before using them. The label is the final authority on how you may legally use any pesticide.

Spider Bites

All spiders (except the family Uloboridae) have venom glands but not all are venemous to man. In fact very few species pose a threat to man. Some spider bites might need medical attention even if the species is recognised as not being venomous to man as secondary infections can occur.

Spider venom, like snakebite venom, is generally either neurotoxic or cytotoxic. Generally, it is the web dwellers that have neurotoxic venom and the non-web dwellers have the cytotoxic venom.

Cytotoxic venom affects the cellular tissue usually restricted to the area of the bite but can spread. The bite is at first painless with symptoms developing about 2-8 hours after the bite. It starts by resembling a mosquito sting, becoming more painful and swollen. Eventually it ulcerates into a large surface lesion (up to 10 centimetres) that will require medical attention. This type of bite would result from members of the genera Loxosceles (family Sicariidae) and Cheiracanthium (family Miturgidae). Treatment with antibiotics might be required to treat secondary infections. The wound will take between two and 4 weeks to heal but the lesion might take months to improve. In some cases ugly scarring might occur that might require plastic surgery.

More specifically, the bite of Cheiracanthium presents as two spots, 4-8mm apart, where the fangs penetrated the skin and are yellow-green, the colour of the venom. After 4-8 hours, mild inflammation, swelling and pain develop. A blister may form over the necrotic lesion after a few days. After this sloughs, an irregular round, ulcerated wound of about 10mm remains. The wound is inflamed, swollen and painful. The wound could start to heal after 10 days but occasionally takes months. In some extreme cases, skin grafts have been necessary. The use of antibiotics is usually required should secondary infections set in but this could be prevented by the use of an antibacterial cream such as Betadine. There is no antivenom and an anti-tetanus injection is usually necessary. Some patients develop a mild fever and headaches after about 3 days and the condition is sometimes misdiagnosed as tick bite fever. However, tick bite fever symptoms develop after about a 10 day incubation period after being bitten, by which stage the bite will have turned black and the surrounding area swollen and red.

The venom of violin spider (Loxosceles) is also cytotoxic with similar symptoms to the sac spider.

Tissue damage from a bite by Sicarius (family Sicariidae) is far more extensive and severe. Bites to humans are not well documented. However, experimental rabbits died within 4-6 hours and autopsies revealed extensive damage to subdermal tissue and skeletal muscle. There was swelling of the liver and damage to heart and kidney tissue as well as blocked pulmonary arteries.

Not everyone will be affected in the same way by a spider bite. The severity would depend on the amount of venom injected, the health of the patient or if the patient has allergies, the age of the patient (small children and the elderly would be more adversely affected) and the site of the bite. Some patients display symptoms of stress that can be misleading, leading one to fear the worst of a harmless spider bite.

Neurotoxic venom affects the neuromuscular junctions, and bite symptoms involving this type of venom are:

·                     severe pain in the chest and abdomen

·                     anxiety, raised blood pressure

·                     breathing difficulties and heart palpitations

·                     nausea and vomiting

·                     sweating, excessive salivation and watery eyes

·                     the body temperature could either fall or rise above normal and the blood pressure may rise with an increased pulse rate

·                     a rash might develop

In this venom category it is only the back button spider, Latrodectus indistinctus, bite that would require urgent medical attention although Latrodectus geometricus envenomation will also require medical attention especially in the case of children, the elderly. 

The main signs and symptoms of Latrodectism (Button spider envenomation):

·                     sharp burning pain at the site

·                     pain spreads to lymph nodes within 15 minutes

·                     severe muscle pain and cramps within an hour, resulting in tightness in the chest and difficulty with walking

·                     anxiety, sweating, fever, slurred speech, nausea and headaches.

Less than 5% of untreated cases result in death, usually as a result of respiratory failure. In fact, there have been no deaths from button spiders in the last 4 to 5 decades. Those more severely affected are children (smaller blood volume) and the elderly who might suffer respiratory or heart failure. Symptoms are less severe with the Brown button spider, Latrodectus geometricus . All Latrodectus bites should be treated and monitored.

When someone is bitten:

·                     Keep the culprit if possible. An identification of the spider would be necessary to determine the appropriate treatment, if any.

·                     Keep the patient or the affected part as motionless as possible. However, this might not be practical if one is out in the wild. It is then preferable to get to help as soon as possible even if the patient has to walk.

·                     Eating, drinking and smoking should be avoided.

·                     Call for medical assistance

·                     Keep the patient on his/her back with feet raised above the rest of the body. Cover with a blanket and keep the head to one side in case of vomiting

·                     Loosen tight clothing

·                     Apply artificial respiration should breathing stop

Apply crushed ice to the affected area. The cold helps to retard the venom action and reduces pain. This must be done within minutes of being bitten. Do not cool for an extended period and remove periodically for the feeling to return otherwise tissue damage might result.

DO NOT

·                     Use alcoholic drinks as this could mask certain symptoms or exacerbate them.

·                     Use potassium permanganate on the wound.

·                     Cut the wound.

·                     Use a tourniquet as this could aggravate local effects of the venom.

·                            Use snakebite venom on spider and scorpion bite patients.

This document to be used as reference only.

All spider bites should be considered dangerous.

If you get bitten by a spider, see your doctor immediately.